Replace OS::MemCopy with OS::MemMove (just as fast but more flexible).

src/platform-posix.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 304 matching lines @@
     if (str.length() > 0)
       str[str.length() - 1] = '\0';
     return -1;
   } else {
     return n;
   }
 }
 
 
 #if defined(V8_TARGET_ARCH_IA32)
-static OS::MemCopyFunction memcopy_function = NULL;
+static void MemMoveWrapper(void* dest, const void* src, size_t size) {
+  memmove(dest, src, size);
+}
+
+// Initialize to library version so we can call this at any time during startup.
+static OS::MemMoveFunction memmove_function = &MemMoveWrapper;
+
 // Defined in codegen-ia32.cc.
-OS::MemCopyFunction CreateMemCopyFunction();
+OS::MemMoveFunction CreateMemMoveFunction();
 
-// Copy memory area to disjoint memory area.
-void OS::MemCopy(void* dest, const void* src, size_t size) {
+// Copy memory area. No restrictions.
+void OS::MemMove(void* dest, const void* src, size_t size) {
   // Note: here we rely on dependent reads being ordered. This is true
   // on all architectures we currently support.
-  (*memcopy_function)(dest, src, size);
-#ifdef DEBUG
-  CHECK_EQ(0, memcmp(dest, src, size));
-#endif
+  (*memmove_function)(dest, src, size);
 }
+
 #endif  // V8_TARGET_ARCH_IA32
 
 
 void POSIXPostSetUp() {
 #if defined(V8_TARGET_ARCH_IA32)
-  memcopy_function = CreateMemCopyFunction();
+  OS::MemMoveFunction generated_memmove = CreateMemMoveFunction();
+  if (generated_memmove != NULL) {
+    memmove_function = generated_memmove;
+  }
 #endif
   init_fast_sin_function();
   init_fast_cos_function();
   init_fast_tan_function();
   init_fast_log_function();
   // fast_exp is initialized lazily.
   init_fast_sqrt_function();
 }
 
 // ----------------------------------------------------------------------------
@@ skipping 202 matching lines @@
   return ntohl(value);
 }
 
 
 Socket* OS::CreateSocket() {
   return new POSIXSocket();
 }
 
 
 } }  // namespace v8::internal